Searchlight with ellipsoid mirror



www3 5R Mlm-iam@ mh HQ@ m zwgw I w i A March 9, 1937. F. R, DlETRlCH 2,072,849

SEARGHLIGHT WITH ELLIPsoID MIRROR Filed Jah. 25, 19:55

Fvn'cdrn'oh Richard Dienck INVENTcar?,

Patented Mar. 9, 1937 UNITED STATES PATENT FFICE Friedrich Richard Dietrich, Pasing, near Munich, Germany Application January 25, 1935, Serial No. 3,416 In Germany January 25, 1934 l Claim.

My invention relates to a search-light having an ellipsoidal reflector, particularly adapted for use in motor vehicles.

As compared with paraboloid reflectors, ellip- 5 scid reilectors distinguish themselves by a con` siderably greater utilization of angle of space, without, however, producing a concentrated long distance light.

My present device produces a suitable light by l means of an ellipsoid reector and utilizes the angle oi space determined by the ellipsoidal shape. In accordance with my invention, I make use of a lens system consisting of at least two lens portions of diiierent optic effect.

l The embodiment herein chosen for illustration is characterized by the arrangement of a dispersing lens directly across the open end of a reflector or semi-ellipsoidal shape, the lens having substantially the same diameter as said 2n open end, and provided on one face with cylindrical flutes.

In the drawing,

Figure l is a vertical cross-sectional view through a search-light of the present character;

:25 and Figure 2 is a iront view of the lens of Figure 1.

The device com-prises a reflector or mirror I of semi-ellipsoidal shape, with a lamp or other source of light 2 mounted therein at the focus of the ellipsoid. A lens I4, having substantially the same'diameter as the forward or open end of the semi-ellipsoid, is arranged -across said end. It has a slightly convex outer face, and its inner face is subdivided into concentric concave p0rtions which define zones of correction I4', I4", and IEW. These zones are convenient because every ray reected by the mirror I falls upon the inner surface of the lens I4 at a dilerent angle, and it would be impossible to obtain a theoreti- 40 cally faultless parallel beam by means of a lens having only a single radius of curvature. The

individual zones of correction I4', I 4, and I4" differ from one another by their various radii of curvature.

By means of the lens I4 an approximately parallel bean of light is produced. In order to provide also for the necessary side illumination,

the lens I4 is provided on its outer surface with cylindrical flutes I5 and I6. These flutes are 5 arranged vertically, the utes IB being of relatively large radius of curvature and occupying the lower part of the lens, the flutes I5 being of smaller radius of curvature and occupying the upper part. The flutes I5 thus spread the light 10 laterally to a greater degree than do the flutes I6.

If desired, the upper portion of the lens, occupied by the flutes. I5, may be colored yellow, so that only a yellow illumination is produced when 15 the device is dimmed, e. g., by means of a screen arranged below a second illament of the lamp 2.

Since the lens I4 is a dispersing lens, the rays reaching it directly from the lamp 2 are dispersed, the center zone HI'" having a slighter 20 dispersing effect and the concentric zones I4" and I4 having correspondingly greater dispersing elects. At the same time, those rays which reach the zone hl" by reflection from the mirror I are caused to be dellected into a substantially forward direction. The result is that I obtain not only a far-reaching, concentrated, long-distance beam, but also a strong and far-reaching side illumination.

What I claim is:

A searchlight comprising a semi-ellipsoid mirror, a source of light at the focus thereof, and a concavo-convex lens secured to the mirror around the opening of the semi-ellipsoid and of substantially the same diameter as said opening, the concave face of said lens having concentric zones of correction of dilerent radii of curvature and the convex face of said lens having groups of cylindrical iutes, the flutes in one group having a different radius of curvature from the ilutes in another group.

FRIEDRICH RICHARD DIETRICH. 

